1. Field of the Invention
This invention or discovery relates to continuous flow grain dryers of the type having a vertical closed top plenum provided with a heated forced air supply. A vertical grain shower passage surrounds the plenum and the heated air in passing through air pervious spaced vertical walls defining the plenum and the passage, dries the showering grain.
2. Description of the Prior Art
A prime example of a grain dryer of the type with which the present invention is concerned is found in U.S. Pat. No. 3,440,734, issued to the present applicants. To any extent necessary, the disclosure of that patent is incorporated herein by reference.
Although the patented structure has proved to be quite successful, it has been found that some grains or grain batches having a relatively high fines content such as chaff or dust cause the ambient air to become unduly loaded with the fines blown from the grain during the drying process. Inasmuch as the heated air supplied to the dryer plenum must for highest efficiency pass through or in contact with open heating means, comprising in the preferred arrangement open gas flames, dust laden air presents a fire or even explosion hazard. Although any grain may present a dust problem, e.g., shelled corn, milo, wheat, barley, oats, soy beans, and the like, a special problem has been encountered with the drying of sunflower seeds. Herein all types of grain which may be dried in this type of dryer will be referred to generically as grain.
In the dryer as disclosed in the aforesaid patent, the air entering the blower for the heated air supply is drawn in at a location near the lower end of the dryer, just above the cool air chamber under the heated air plenum. Therefore, where the ambient air, from which the air for the heated air blower system is derived, is heavily laden with fines the hazards just mentioned are of considerable concern.